Did Rob McKenna just cost himself the governor’s mansion?

Democrats believe the political juggernaut that is Rob McKenna may have just been tripped up.

On Monday McKenna, the state’s Republican attorney general, said he’d join GOP colleagues and sue to stop the Democrats’ comprehensive health care reform law from taking effect. President Barack Barack Obama on Tuesday morning signed the measure passed by his party in dramatic fashion Sunday night.

McKenna

“I believe this new federal health care measure unconstitutionally imposes new requirements on our state and on its citizens. This unprecedented federal mandate, requiring all Washingtonians to purchase health insurance, violates the Commerce Clause and the 10th amendment of the US Constitution,” McKenna said in a statement.

Gov. Chris Gregoire and her fellow Democrats wasted no time attacking McKenna.

“I completely disagree with the Attorney General’s decision and he does not represent me,” the governor said. “This is landmark legislation that will cover over 32 million Americans who don’t have health care. I have made it clear to the Attorney General that I will actively oppose this lawsuit if it moves forward.”

Make no mistake, Democrats have been waiting – praying, actually – for something to use against McKenna. The attorney general and former King County councilman represents the only real threat to the Dems’ continued dominance in Evergreen State politics.

His base of support is in King County, a virtual wasteland for the GOP. He’s personable and sharp, able to argue policy with the best of them. And he’s spent his years as A.G. burnishing his credentials as someone willing to fight for consumers.

Seen as the frontrunner for the governor’s race in 2012, Dems were going to have a hard time demonizing him. At least until Monday.

Believe me, eager party operatives are already envisioning the attack ads they’ll unleash against McKenna. They’ll be something along the lines of: “Rob McKenna, the tool of the evil insurance industry, wants to deny hundreds of thousands of state residents the affordable medical care they need.”

McKenna’s good, but a counter ad detailing the complexities of the Commerce Clause and the 10th Amendment will fall flat.

Rep. Jay Inslee, D-Wash., is considering a gubernatorial run himself.

“We fought over 2,000 insurance industry lobbyists in Washington DC to protect Washingtonians health care, we shouldn’t have to fight our own Attorney General too,” Inslee said late Monday night. “Stripping families of their legal rights to insurance, may be the South Carolina way, may be the insurance company way, may be the Tea Party way, but it’s not the Washington way.”

Ouch.

From a purely political standpoint, it does appear that McKenna blew it.

Check out the other states that are suing – Florida, South Carolina, Alabama, Nebraska, Texas, Pennsylvania, Utah, North Dakota, and South Dakota. With the exception of Pennsylvania, all those places are fairly to very conservative.

Washington is not. The state’s two senators and governor are Democrats. Six of the nine U.S. House members are also Dems. Republicans have a hard time winning in Washington because Democrats have successfully portrayed them as scary, right-wing ideologues.

McKenna was looking like the exception. Democrats will now try to tar him with the same brush they’ve used to dispatch every GOP gubernatorial candidate for the past 25 years. And it looks like McKenna has just given them at least some of the paint they’ll need.